Separating system



J. M. LE GRAND 1,898,733

SEPARATING- SYSTEM Filed July 27. 1928 5 Sheets-Sheet l Feb. 21, 1933. J. M. LE GRAND 1,898,733

SEPARATING SYSTEM Fued July 27. 1928 3 sheets-sheet 2 //V VET/V 7 0/13 SEPARATING SYSTEM Filed July 27. 1928 J. M. LE 'GRAND j 5 sheets-sheet 3 Patented Feb. 21, 1933 UNITED STATES PATENT oFFlcE JOSEPH I. LE GRAND, OF NEWARK, NEW JERSEY, ASSIGNOB T CARRIER ENGHBEBING OOBPOBATION, 0F NEWARK, NEW JERSEY l BEPARATING SYSTEM.

Application iled July 27,

This invention relates to a pneumatic separating system, and particularly to the type which may be advantageouslgn utilized in transferring and separating ely divided `g particles of solid matter, as for example, in cement or gypsum mills, ball mills, tube mills, chilean mills, etc., where it is desired to transfer the line particles or dust and often classify them into different grades according to size.

An object of the invention is to generally improve separating systems of this type.

A further object of the invention is to provide an improved system with which the particles maybe separated according to sizes, which will be exce tionally eicient and economical in operatlon, compact, require a minimum of power and operating attention, operate uniformly for all sizes of zo particles to be handled and separated, and

which will be relatively simple and inexpensive.

A further object of the invention is to provide an improved pneumatic separating system with which the transfer medium for the nely divided particles may be efec tively and eiciently handled to effect separation of the particles with maximum eiliciency.

so Various other objects and advantages will be apparent from the following descri tion of embodiment of the inventlon, an the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings Fig. 1 is a side elevation of, a system constructed in accordance with this invention;

Fig. 2 is a plan of the same; with parts v broken away to show other parts otherwise hidden thereby;

Fig. 3 is an elevation of part of the system, with the trap in section and on a larger scale;

Fig. 4 is a sectional elevation through the mill which serves as a course of finely divided particles to be transferred, graded and.

separated, and illustrating the adaptation thereto of a pneumatic system forming the subject matter of this invention;

192s. serial no. :395316.

Fig. 5 is a sectional plan through the trap, with the section taken approximately along the line 5 5, Fig. 3; and

Fig. 6 is a sectional plan of another portion of the trap, with the section taken approximately along the line 6--6 of Fig. 3.

In the illustrated embodiment of the invention and referring particularly to Fig. 1, the source 1 of the iinely divided particles may be a mill or pulverizing device of any 60 suitable or desired construction, the details of which Iper se form no part of the present invention. The coarse material to be pulverized or finely divided'may, for example, b e contained in a suitable storage bin 2 from 65 which it descends by gravity in a conduit 3 into the interior of the mill.

From the interior of the mill, a duct or conduit 4 extends to a trap 5, and from the trap 5 another duct or conduit 6 extends to 70 the intake side of a suitable blower -7 which may be driven by any suitable source of power such as a motor 8. The blower 7 at its output side is connected to a duct or conduit 9 which communicates with a-` distrib- 75 uting belt or chamber 10 surrounding the mill 1.

The finely divided particles which are deposited in the trap 5 may be removed through a spoutlike terminal 11 which is normally 80 closed by a plate or valve 12 of any suitable construction.

Referring now particularly to Fig. fl, the chamber 10 extends around the periphery of the mill and is provided with a series of ejector nozzles 13 which are arranged at different points around and on opposite sides of the mill and directed downwardly and convergingly into the portion of the mill where the finely divided particles are produced, that is, where the pulverizing occurs. The air entering the mill from the nozzles 13 will be discharged into the mill in jets at a high velocity.

The jets inl striking the freshly divided particles, or the particles in the storage space, will stir up and. agitate the particles and place the lighter portions thereof in suspension in the air thus introduced into/the mill.

The higher the velocity of the air discharged by the nozzles 13, the greater the agitation of the particles and therefore'the larger will be the particles which are`taken up and placed in suspension in the discharged air. The chamber 10 also is provided with any desired number of nozzles 14 which are upwardly directed, that is, directed somewhat toward the outlet from the mill so as to have an ejector action upon the air discharged through the nozzles 13 and carrying the iinely divided particles in suspension.

The air discharged by the nozzles 14 will thus accelerate the removal of the air carrying the particles in suspension, and the air discharged from both sets of nozzles will be removed from ,the mill through the duct 4. The pulverizing mechanism of the mill 'is located in a chamber 15 into which the jets of air are discharged from the nozzles 13 and 14 and this chamber 15 preferably tapers or converges upwardly toward its connection to the conduit or duct 4.

The tapered or converging chamber 15 with the nozzles 14 discharging upwardly toward the converging end thereof functions somewhat in the nature of aVenturi passage in which the discharged air is accelerated in movement so as to carry with it the particles which are then in suspension` therein.

Referring now particularly to Fig. 3, the particle laden air moving along the conduit 4 is carried into the trap 5. This trap 5 may comprise a suitable casin having an lnternal partition 16 dividing it into separate upper and lower chambers 17 and 18.

The casing of the trap 5 is preferably approximately circular in horizontal cross section, and the duct or conduit 4 opens into the upper chamber 17 of the trap casing in a direction approximately tangentially of thaty chamber, so that the air entering the trap will first be given a swirling movement or travel around the border of the chamber 17.

A channel member 19 may be tted against the outer wall of the casing of the trap, so as to form with the inner surface of that wall a duct 20 which extends spirally along the portion of the inner periphery of the trap and between the chambers 17 and 18 on opposite sides of the partition 16. One end of the duct 20 opens into the upper chamber 17 along the inner periphery of the lateral wall thereof, and the other end opens into the Chamber 18.

The duct 20 extends in the direction of the swirl of the air entering the chamber 17, so that as the particle laden air moves or swirls along the side wall of the chamber 17 a portion of the swirling air with a large percentage of particles thrown outwardly by centrifugal force will enter the duct 2O and be carried into the lower chamber 18. Theremainder of the air swirling in the chamber will continue to swirl and be crowded centrally of the chamber 17 by the continued entrance of other air tangentially of the cham-y ber until it reaches the outlet into the suction duct 6 leadin to the fan or blower 7.

The duct 6 pre erably extends downwardly into the chamber 17 for some distance, such as to an'approximately central point thereof. A second duct or passage 21 is supported within the duct 6 in any suitable manner and abutting a horizontal annular partition 22 extending between the interior of the duct 6 and this passage or duct 21. The duct 21 opens at its upper end into the duct 6 at a point well within theduct 6 and descends outof theiduct 6 and through the partition 16 well into the interior of the lower chamber 18 of the trap.

The duct 6 will therefore have two branches, one of which is the opening or passage through the duct 21 into the chamber 18, and the other'of which is the passage between the duet 21 and the walls of the duct 6 and opening into the chamber 17 The suction side of the fan or blower 7 will thus connected to both chambers 17 and 18 so as to withdraw air from both and thus cause movement of air through both chambers.

The lower end of the duct 21 may support a balile plate 23 in any suitable manner, such as by ears or lugs 24 which extend upwardly therefrom and slide along the inner periph-` ery of the duct 21. Suitableguide pins 25 or guide screws 26 may pass through slots 27 and 28 in the lugs 24 and the walls of the duct 21 respectively, so as to permit limited adjustment of the baile plate 23 toward and from the open lower end of the duct 21. By

tightening the screws 26, the baliie plate may be clamped in any of the positions into which it may be adjusted. The air from the chamber 18 may pass around the baile plate and between the lugs 24 into the open lower end of the duct 21.

Avalve plate 29 (see particularly Figs. 3 and 6) is rotatably supported upon the partition 22 which extends from the inner periphery of the duct 6 and supports the duct 21. This plate 29 is annular in shape and may have a plurality of lugs 30 projecting from its inner periphery and bent downwardly into the duct 21 so as to serve as a guide for the plate 29 in its rotary movement.

Angle guides 22a in the duct 6 confine the valve 29 to the partition 22. An operating arm 31 may extend outwardly through a slot 32 in the wall of the duct 6, the slot 32 extending arcuately or peripherally of the duct so as to permit of a limited rotary movement of the plate 29 about the axis of the duct 6.

The annular partition 22 and the annular plate 29 are both provided with a series of apertures 33 and 34 respectively, which may be brought into and out of alignment with one another upon the rotary movement of the plate 29 as caused by movement of the operating arm 31.

Thus the effective passage leading from the duct 6 into the upper chamber 17may or passage through the duct 21 between the uct 6 Vand the lower chamber 18 of the t ap. The damper may have an operating ro`d 36 extending exteriorly through the duct 21, and also through the duct 6 and trap 5, with the outer end terminating in an operating handle 37 to permit adjustment of the damper 35 from the exterior of the trap.

A. cylindrical shell or sleeve 38, Fig. 3, is disposed within the lower end of the duct 6, and spaced from the walls thereof, so as to provide with the duct 6 an annular chamber 39. This shell 38 may be suitably supported at its upper end from the duct 6, and its lower end depends slightly below the lower end of the duct 6, and terminates in an outwardly flared or oblique iiange 40.

A pipe or duct 4l, connected to the discharge pipe 9 leaving the output side of the fan or blower 7, is connected to the chamber 39 between the shell 38 and the lower end of the duct 6. This duct 41 has a valve 42 therein by which the flow of the air under pressure from the fan or blower 7 to the chamber 39 may be selectively and variably regulated. The air thus delivered to the chamber 39 will be discharged from the lower end thereof between the lower end of the duct 6 and the oblique. llange 40, thusv creating a frustoconical air wall. or air curtain interposed between the outlet from the duct 6 into the chamber 17 and the inlet from the duct 4 into the chamber 17. v

In order to regulate the thickness of this annular air curtain or wall, la ring 43 ma be interposed between the shell 38 and the lower end of the duct 6 and suitably mounted on the lower end of the duct 6, so that it can be adjusted verticall to a limited extent. The ring 43 closely ts the inner periphery of the lower end of the duct 6 and therefore Y is spaced somewhat from the outer surface of air from the chamber'39 to form the air,

wall or curtain. Thus the spacing between the lower end of the ring 43 and the fl e 40 will determine the thickness of this air studs 44 extending` curtain or wall. Obviously, any suitable means for clamping the ring 43 in any ad# justed position may be employed.

A; by-pass duct 46`having therein a ow regulating valve or member 47 may be connected between the ducts 4 and 9, so that selected proportions of the circulating air may be by-passed around themill in order to regulate the fineness of the particles which will be taken up and removed from the millor source of the particles. 46 is preferably adjacent the mill or source 1, so as to maintain independently ofthe rate of air flow through the mill or source 1, an approximately `uniform oraY constant flow through the duct 4 and carry into the trap through duct 4 all particles reaching that duct. It will be noted that the ducts 4, 6, 9, and 46 form with the trap 5, the blower 7 and the mill 10, a closed circulatory system through which air or other luid medium is repeatedly circulated for transferrin the finely divided particles from the mill or source 1 to the trap 5, in which trap the particles are separated from the transfer me- The by-pass duct` In the operation of such. a system, the

blower 7 will be operated preferably at a constant rate of speed from the motor 8, and the material to be pulverized may be stored in the bin 2. The mill 1 is operated to pulverize or reduce to a finely divided condition in any suitable or desired manner the material which descends to the mill from the bin 2 through the duct 3.

The air from the blower 7 is forced under lpressure through the duct 9 to the chamber 10 extending around the mill or source, and

sion in the air thus discharged. j

The discharged air then moves into the duct' 4 and carries with it some of the particles in suspension therein. This upward movement of the particle laden air through the converging chamber 15 to duct 4 is accelerated by the ejector action of the nozzles 14 which direct another portion of the air fromthe chamber 10 upwardly toward the duct 4. Thus a very positive upward circulation of air in'the chamber 15 is induced,

and any solid particles in the mill which have been agitated and momentarily held in suspension in the air discharged from the noz- -zles 13 will be carried with the air upwardly through the duct 4 and then discharged into the up r chamber 17 in a direct-in tangentially t ereof. The air and particles thus dischargedv into the chamber 17 swirl around this chamber, and the air andI some ing the blower 7 will be admitted to the. 4o4

of the lighter particles will gradually work more or less spirally toward the center of the chamber, and then pass into the space between the duct 21 and the shell 38. The heavier particles will be thrown outwardly by centrifugal force and heldby that force in the swirling air along the periphery of the chamber until they pass through duct 20 into the second or lower chamber. The air entering the outlet surrounding the duct 2l will pass through apertures 33 and 34 into the duct 6- and return to the fan or blower 7.

A portion of the swirling, particle laden air in the chamber 17,'particularly some of the freshly introduced or more actively swirling air, with the heavier particles held in the outer layer of swirling air by centrifu- 'gal force will enter the duct 20 and by its inertia and the vacuum in the lower chamber 18 will descend into the lower chamber. This descending air will swirl around the chamber 18 in a manner similar to that in the chamber 17, and the heavier particles will be thrown outwardly by centrifugal force and will descend into the lower part of the chamber 18 which serves as a receiving receptacle or bin'.

The damper 35 and the annular plate valve 29 will beso adjusted relatively to one another that there will be partial vacuum or suction in the lchamber 18 preferably slight,-N ly higher than in the chamber 17, so as to assist in the movement of a portion of the particle laden air from the chamber 17 into the lower chamber through the duct 20. The baille plate 23 prevents direct discharge of the incoming air into the duct 21.

At the same time, a portion of the air leavchamber 39 and discharged downwardly over the flange 40 as an annular wall or curtain. This wall will prevent movement of the ingoing air directly to the outlet at the lower end of the duct 6, and will compel it first to swirl around the outer part of the chamber 17, during which the heavier parti cles will of course be thrown by centrifugal force outwardly along the outer wall of the chamber 17 and by the continued swirling held along the outer periphery until they pass through the duct 20 into the lower chamber where they can separate from the swirling an'.

The swirlin air in the chambers 17 and 18 of the Vcontinued introduction of air tangentially vof the chamber, and as the air works centrally, it will lose the heavier particles carried thereby before it reaches and passes into the ducts 21 or 6. s

Some of the particles will undoubtedly be recirculated time and Aagain before being separated from the air. A\certain amount of the material is constantly being separated in the trap, and a certain amount is constantly being added to the mill, so that the operation is continuous. At intervals, the separated or deposited finely divided particles may be removed from the chamber 18 through the lower spout 11 thereof.

Inasmuch as a rapidly moving current of air will carry larger articles in suspension than a current of air moving more slowly, advantage is taken of this .fact in determining to some extent the size of the particles which will be removed from the mill 1 and deposited in trap 5. If the velocity of air through the mill is relatively slow, only the finer particles will be taken up, and when the velocity is increased, the larger or heavier particles will bepicked up and carried to th trap 5. y

While this change in velocity of air through the mill might -be obtained by varying the speed of the blower 7, this would be an impractical arrangement because with the decrease in speed of the blower 7, there will be a decrease of the suction in the chambers 17 and 18, and consequently a loss of efiiciency in the trap. It is; therefore, important that the blower 7 be operated at a constant speed and some other arrangement provided for vailying the rate of the air flow through the m It should also be noted that if the speed of the blower 7 is decreasedl the rate of travel also be decreased, and its capacity for handling and carrying the particles will be very greatly interfered with. Therefore it is important that the speed ofthe blower 7 and the rate of air flow in passage 4 be maintained fairly constant.

In accordance with this invention, the bypass 46 is utilized for short circuiting a portion of the air approaching the mill.

Thus, upon operation of the valve 47, more or less of the air delivered by the blower 7 will be by-passed around the mill and delivered into the duct 4 closely adjacent the mill, so that the air flowing along the conduit 4 will be substantially constant in rate of flow. At the same time the air flow through the mill itself may be decreased, so that only the finer particles will be taken up into suspension, and when picked up they will althe quantity of air necessarily handled, sol

that less power is required for operation of the system. The size of the particles removed and deposited in trap 5 may also be selectively varied without interferring with the efficiency of the operation of the system.

In the foregoing description, I have, for

convenience, used the word air asdesignating the circulating uid medium, by means of which the transfer and separation of the solid particles is obtained, but it will be understood that I contemplate, and by the term air intend to include within the scope of the invention, any other fluid medium whose use may be found desirable.

It will be obvious that various changes -in the details which have been herein' described and illustrated'in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim: 1. In a pneumatic separating system, a

' source of finely divided particles, a delivery duct leaving said source, a single air supply duct leading to said source and directing jets of air to said source in a manner to agitate the particles therein and place them in suspension in the supplied air, means for causing a ilow of air-through said ducts and source by pressure diierences to carry oi particles placed in suspension in the air at said source, and means for by-passing a selected portion of air around said source from the air supply duct into saiddelivery duct ad]acent the inlet end thereof to vary the ineness ofthe particles removed thereby, and maintain a constant velocity of the air 1n said delivery duct.

2. In a pneumatic separating system, a trap, a blower, a source of finely divided partlcles, and duct means connecting said blower, trap and source in a closed circula# tory system through which air is circulated by said blower, said duct means including an ejector nozzle for discharging a portion of the circulating air into the particles of said source to agitate and placein suspension 1n the clrculatmg air partlcles to be removed from said source, and another nozzle for discharging another portion of the circulating a1r 1nto.sa1dsource at a high velocity and in a dlrectlon to accelerate departure from said source of. the first mentioned portionof the ancarrymg particles in suspension.

3. a pneumatic separating system, a trapZ a blower, a source of iinel divided partlcles, duct means connecting said blower, trap and source in a closed circulatoryvsystem through which air is circulated by said' blower, said duct means including an outlet 'from said trap and an inlet to said trap at a point spaced from said outlet, and an additionalair duct connected to the pressure'side of said blower and openin into said trap with a substantially long an harrow slit for discharging a part of the air from said blower into said trap as a substantially continuous sheet wall of air separating said inlet and outlet, to forma sheet-like air curtain preventing direct travel of the circulating air from the inlet to the outlet in said trap.

4. Inl a pneumatic separating system, a separating chamber having inlet and outlet spaced apart, a source of flnely divided particles, a blower, a duct system connecting said source, said blower and the inlet and outlet of said chamber in a closed circulatory system, and means for removing a portion of the air leaving said' blower and discharging it into said chamber as a substantially continuous sheet wall across the path between saidinlet and outlet so that the entering ,air will be prevented from passing directly to said outlet upon entering said chamber.

5. In a pneumatic separating system, a separating chamber having inlet and outlet spaced' apart, asource of inely divided particles, a blower, a duct system connecting said source, said blower and the inlet and outlet of said chambers in a closed circulatory system, and means forremoving a portion of the air leaving said blower and discharging it into said chamber as a substantially` continuous sheet wall between said inlet and outlet whereby the entering air will be prevented from passing directly to said outlet upon entering said chamber, said last` named means being operable to selectively vary the portion of air directed into saidchamber di- Nrectly from the blower to Jliorm the air curtaln.

6. In a pneumatic separating system, a u

trap, a blower, a source of `finely dividedl particles, and duct means connecting said blower, trap and source in a closed circulatory system through vwhich air is circulated by said blower, said duct means including a variable by-pass around ,said source and re-entering'said duct means at the exit end of said source, and operable to vary the proportion of air passing through said source, whereby the fineness of the particles removed .from Said source may be varied independently of the air flow through said system.

7. In a pneumatic separating system, a mill for producing finely divided particles,

a delivery duct having an opening into said mill to receive therefrom air and suspended particles, means forl directing a blast of air into the working part of said mill to stir up the finely divided particles, place them in suspension in the air, and convey them into said duct, and means for injecting into said mill a further blast of air in a direction somewhat towards said duct opening to accelerate the movement into and along said duct of the air of the fast blast and the particles carried in suspension thereby.

K 8f In a pneumatic separating system, the method which comprises directing a jet of air into a quantity of finely divided particles with suspended particles to another locality, disc'hargmg a jet of additional air into the moving air in the direction of travel of the particle-laden air to aid the transfer of the suspended particles and to hold them in suspension while being moved, and then separating the particles from the suspending t JOSEPH M. LE GRAND. 

